Im really bad at chemistry help!

a) sodium and chlorien atoms bond to form salt molecules

Explanation:

Pretty much all the other reactions can be reversed. Ice melting to form water can go back to being ice under freezing temperatures. H2O is H2O. It doesn't become a new compound due to temperature changes unless it is introduced to other elements. Carbon dioxide freezing to forming dry ice is typically a physical rxn. Salt and water mixing to form salt water although is chemical, can be easily reveresed if you were to boil off the water: all that would remain is salt.

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml